The present invention relates to a radiation sensitive composition which is insolubilized by radiations such as light, electron beam and X-ray and a process for formation of patterns using the composition.
Reduction projection exposure is mainly employed for photolithography in preparation of integrated circuits and large scale integrated circuits. When reduction projection exposure is employed, if size of pattern to be formed is in the submicron area, contrast of aerial image of light which has passed through an optical system is decreased even if contrast of mask pattern is high. As an approach to improve this reduction in contrast, for example, Japanese Patent Kokai No. 59-104642 has proposed a process for formation of resist pattern wherein a layer containing an aryl nitrone compound is formed on a photoresist film, thereby to enhance contrast of image which has been reduced in contrast due to exposure system. However, this process does not give consideration to deformation of pattern caused by reflected light from substrate and that caused by light absorption by the photoresist per se and thus has suffered from the problem of reduction in resolution. The photoresist also senses the reflected light from substrate, resulting in inferior shape of pattern. When absorption by the photoresist per se is great, light absorption occurs at the upper part of the photoresist film and the resulting pattern has section of reversed trapezoid (in case of negative type) In both the cases, resolution is deteriorated.